An animatronic device is an animated device with motion likeness of a human, creature, or animal. Conventional animatronic devices include animatronic puppets, robots, creatures, special effects make-up, scenic props, sets, etc. These devices find wide use in themed rides, dark walks, scenery, and special effects for the film and television industries.
Motion for an animatronic device is typically powered by an electric or mechanical source. The most common source of power for an animatronic device is electric motors such as AC, DC, servo, and stepper motors. Compressed air and pressurized hydraulic fluid are also used to power air and hydraulic motors in larger animatronic devices. Each of these forms of power has advantages and disadvantages that determines its usage.
AC and DC motors provide continuous rotary output, which is often not suitable for simple animatronic devices. For example, a simple animatronic device may require a lead screw and other mechanical assistance to convert continuous rotary output of a motor into simple linear motion. AC motors provide continuous rotary motion but are limited to a few speeds that are a function of the AC line frequency, e.g., 1800 and 3600 rpm based on 60 Hz in the U.S. If other outputs speeds are desired for an animatronic device, a gearbox speed reducer is required; thus further complicating the animatronic device. Servomotors are fast response, closed loop control motors capable of providing programmed motion. In addition to the above rotary to linear complications, these devices are also very expensive. Unlike servomotors, stepper motors are open loop, meaning they receive no feedback as to whether the output device has responded as requested. While being relatively good at holding an output in one position, stepper motors often are poor with motion, get out of phase with a desired control, moderately expensive, require special controllers, and thus not ideal for many animatronic devices.
Air and hydraulic motors have more limited application in animatronics than electric motors since they require the availability of a compressed air or hydraulic source. The additional weight, complexity and relative inefficiency of the power source makes these devices unsuitable for many animatronic applications, particularly for small mobile devices, since extremely small compressors and valves are currently unobtainable. Although individual air motors and air cylinders are relatively cheap, these pneumatic systems are also quite expensive when the cost of all the ancillary equipment is considered.
In addition to the specific drawbacks discussed with respect to each source of power, all of the above systems are generally heavy, bulky and not suitable for many applications where light weight and small size is desirable. Conventional electromagnetic technologies also typically do not have sufficient energy densities (the work output on a per volume or per mass basis) to construct many animatronic devices. The deficiency of many conventional devices is greater at small scales. As electromagnetic devices are scaled-down in size, their efficiency decreases. Further, the above technologies provide strict mechanical output. Many animatronic applications require a high degree of mobility or dexterity that is difficult to achieve with conventional actuation technologies.
In view of the foregoing, alternative devices that convert from an input energy to mechanical energy would be desirable.